[PATCH v10 11/15] s390/vfio-ap: Transition device migration state to from/to STOP

[Anthony Krowiak <akrowiak@linux.ibm.com>]

VFIO_DEVICE_STATE_RESUMING to VFIO_DEVICE_STATE_STOP
VFIO_DEVICE_STATE_STOP_COPY to VFIO_DEVICE_STATE_STOP
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Terminates the data transfer session of the vfio-ap device state
between the source and target hosts. Release the migration file
state (ap_config buffers and file pointers) so that a subsequent
migration captures a fresh AP configuration rather than serving
stale data. Since the vfio-ap device does not virtualize a DMA
device, there is no internal device state to incorporate into the
vfio-ap device on the target, so return NULL since no file stream
is needed in the STOP state.

VFIO_DEVICE_STATE_STOP to VFIO_DEVICE_STATE_RUNNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Migration has been cancelled. Release the migration file state so
that a subsequent migration captures a fresh AP configuration
rather than serving stale data.

VFIO_DEVICE_STATE_RUNNING to VFIO_DEVICE_STATE_STOP
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Migration has not yet been initiated. No migration file state
exists to release, so just return NULL.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_migration.c | 66 ++++++++++++++++---------
 1 file changed, 44 insertions(+), 22 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
index 469fa09ec908..cf38407d1b15 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -196,6 +196,8 @@ static void vfio_ap_release_resuming_file(struct vfio_ap_migration_data *mig_dat
 	mig_data->resuming_mig_data_complete = false;
 }
 
+static void vfio_ap_release_mig_files(struct ap_matrix_mdev *matrix_mdev);
+
 static int vfio_ap_release_mig_file(struct inode *file_inode, struct file *filp)
 {
 	struct ap_matrix_mdev *matrix_mdev = filp->private_data;
@@ -939,6 +941,9 @@ static int do_post_copy_validation(struct ap_matrix_mdev *matrix_mdev,
 {
 	const char *mdev_name = dev_name(matrix_mdev->vdev.dev);
 
+	lockdep_assert_held(&ap_attr_mutex);
+	assert_has_update_locks_for_mdev(matrix_mdev);
+
 	if (source_config->magic != VFIO_AP_MIG_MAGIC ||
 	    source_config->version != VFIO_AP_MIG_VERSION)
 		return -EINVAL;
@@ -950,15 +955,6 @@ static int do_post_copy_validation(struct ap_matrix_mdev *matrix_mdev,
 	return verify_ap_configs_are_compatible(mdev_name, source_config);
 }
 
-static int do_post_copy_processing(struct ap_matrix_mdev *matrix_mdev,
-				   struct vfio_ap_config *ap_config)
-{
-	lockdep_assert_held(&ap_attr_mutex);
-	assert_has_update_locks_for_mdev(matrix_mdev);
-
-	return do_post_copy_validation(matrix_mdev, ap_config);
-}
-
 static ssize_t vfio_ap_resuming_write(struct file *filp, const char __user *buf,
 				      size_t len, loff_t *pos)
 {
@@ -1052,7 +1048,7 @@ static ssize_t vfio_ap_resuming_write(struct file *filp, const char __user *buf,
 		}
 
 		if (*pos == (loff_t)expected_sz) {
-			ret = do_post_copy_processing(matrix_mdev, ap_config);
+			ret = do_post_copy_validation(matrix_mdev, ap_config);
 			matrix_mdev->mig_data->resuming_mig_data_complete = !ret;
 		}
 	}
@@ -1146,20 +1142,46 @@ vfio_ap_transition_to_state(struct ap_matrix_mdev *matrix_mdev,
 		return filp;
 	}
 
-	if ((cur_state == VFIO_DEVICE_STATE_RESUMING &&
-	     new_state == VFIO_DEVICE_STATE_STOP) ||
-	    (cur_state == VFIO_DEVICE_STATE_STOP_COPY &&
-	     new_state == VFIO_DEVICE_STATE_STOP)) {
-		/* TODO */
-		return ERR_PTR(-EOPNOTSUPP);
+	/*
+	 * Terminates the data transfer session of the vfio-ap device state
+	 * to the destination guest.
+	 */
+	if (cur_state == VFIO_DEVICE_STATE_RESUMING &&
+	    new_state == VFIO_DEVICE_STATE_STOP) {
+		if (!mig_data->resuming_mig_data_complete)
+			return ERR_PTR(-EINVAL);
+
+		/* Set resuming_mig_data_complete to false for clean reuse */
+		matrix_mdev->mig_data->resuming_mig_data_complete = false;
+		vfio_ap_release_resuming_file(matrix_mdev->mig_data);
+		return NULL;
+	}
+
+	/*
+	 * Terminates the transfer session of the vfio-ap device state from
+	 * the source guest.
+	 */
+	if (cur_state == VFIO_DEVICE_STATE_STOP_COPY &&
+	    new_state == VFIO_DEVICE_STATE_STOP) {
+		vfio_ap_release_stop_copy_file(matrix_mdev->mig_data);
+		return NULL;
+	}
+
+	/*
+	 * These states indicate migration has either not been initiated or
+	 * has completed and the vfio-ap device is operating normally. Since the
+	 * vfio-ap device does not virtualize a DMA device, there is no internal
+	 * device state to incorporate into the vfio-ap device on the target.
+	 */
+	if (cur_state == VFIO_DEVICE_STATE_STOP &&
+	    new_state == VFIO_DEVICE_STATE_RUNNING) {
+		vfio_ap_release_mig_files(matrix_mdev);
+		return NULL;
 	}
 
-	if ((cur_state == VFIO_DEVICE_STATE_STOP &&
-	     new_state == VFIO_DEVICE_STATE_RUNNING) ||
-	    (cur_state == VFIO_DEVICE_STATE_RUNNING &&
-	     new_state == VFIO_DEVICE_STATE_STOP)) {
-		/* TODO */
-		return ERR_PTR(-EOPNOTSUPP);
+	if (cur_state == VFIO_DEVICE_STATE_RUNNING &&
+	    new_state == VFIO_DEVICE_STATE_STOP) {
+		return NULL;
 	}
 
 	/* vfio_mig_get_next_state() does not use arcs other than the above */
-- 
2.53.0